BeebOPL: an FM Synthesiser for the BBC Micro

for bbc micro/electron hardware, peripherals & programming issues (NOT emulators!)
User avatar
JudgeBeeb
Posts: 808
Joined: Thu Sep 10, 2015 8:56 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by JudgeBeeb » Sun Aug 28, 2016 7:24 pm

Managed to get the basics of a DRO player working at Cambridge this weekend. DRO (DOSBox Raw OPL) files are a way of capturing OPL data from any compatible DOS program. Essentially, one runs the DOS program from within DOSBox and it creates a file of the OPL instructions captured from that program. The resultant file can then be played back on the Beeb through the BeebOPL card.

By way of an example, I was able to capture the OPL data from the JukeBox program that shipped with the original AdLib card. That files was then played back on my Model B and the audio was then recorded directly from the prototype BeebOPL card connected to my Model B.
William Tell.mp3
(1.62 MiB) Downloaded 235 times
There is so much wonder in the universe; why should you want to imagine that there is more?


User avatar
JudgeBeeb
Posts: 808
Joined: Thu Sep 10, 2015 8:56 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by JudgeBeeb » Thu Oct 20, 2016 8:37 pm

thecellartroll wrote:Some tunes that work quite nicely...
https://www.dropbox.com/s/hs6jce8xdxmyujt/OPL1.ssd?dl=0
Nice! :D

Were you using Reality Adlib Tracker (RAD) to stream these? It looks like you have come across my pet annoyance. Many of these tracks are coded to auto-repeat endlessly and it's very difficult to get DOSBox to stop stream at a natural break.

I believe it is possible to stop the repeats, by using the 'Order Editor' in RAD but that is activated by the 'apostrophe' key and for some reason, I can't get DOSBox to recognise mine. :?
There is so much wonder in the universe; why should you want to imagine that there is more?

thecellartroll
Posts: 191
Joined: Thu Nov 24, 2011 10:43 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by thecellartroll » Thu Oct 20, 2016 8:41 pm

Yes! And yes. The repeat made me try to stop the recording at the right place.

I also streamed some MIDI files but mostly they turned out awful. I can post them if people want though.

User avatar
JudgeBeeb
Posts: 808
Joined: Thu Sep 10, 2015 8:56 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by JudgeBeeb » Thu Oct 20, 2016 8:52 pm

thecellartroll wrote:I also streamed some MIDI files but mostly they turned out awful. I can post them if people want though.
A couple of things to note. First, the DOSBox OPL2 emulator is not quite as good as it might be. Some of the 'awful' MIDI files sound a lot better when played through native hardware. Secondly, there seem to be a few different OPL2 MIDI drivers. The ones I have found are in a program called MIDIer (which wasn't particularly good); Windows 3.1; and Windows 95. The Windows 95 one is (mostly) the best driver.

I agree that they are often quite poor. The problems seem to be that either they are encoded in more than 9 voices (in which case, any voice numbered above 8 are simply ignored, notwithstanding that those voices may contain crucial parts of the melody) and that the background rhythm is often played much louder than the melody.

But you can get some good results. Most of the tracks in the 'music' folder in my GitHub repo are in fact streamed from MIDI. Have a listen to STRWARS and WHEN64 which I added last night.

But, ultimately, tracks specifically written for OPL2 are always going to sound the best.

At present I am working on some routines to get into programming the card directly. However, given my novice status in terms of coding, and my complete lack of any musical talent or knowledge, that may be hopelessly optimistic.
There is so much wonder in the universe; why should you want to imagine that there is more?

thecellartroll
Posts: 191
Joined: Thu Nov 24, 2011 10:43 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by thecellartroll » Thu Oct 20, 2016 9:33 pm

Yeah, some are not too bad. But it looks like some time ago you went on exactly the same Google mission as me!

Sincerely, thanks for this project. Great fun. Now I really must build the BeebSID!

User avatar
tricky
Posts: 3585
Joined: Tue Jun 21, 2011 8:25 am
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by tricky » Mon Oct 31, 2016 1:12 pm

Should have checked on Saturday, can these be powered from the aux socket under the beeb or from the internal 5v lines?

User avatar
JudgeBeeb
Posts: 808
Joined: Thu Sep 10, 2015 8:56 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by JudgeBeeb » Mon Oct 31, 2016 2:01 pm

tricky wrote:Should have checked on Saturday, can these be powered from the aux socket under the beeb or from the internal 5v lines?
Absolutely. I have one inside my Master 128 that is powered by tapping off one of the PCB power connectors. The Beeb's 5V signal is clean enough for the board and it only draws 30mA so isn't going to represent any significant demand on the PSU.

If you are planning on mounting it internally, you may wish to consider a power header rather than the barrel connector - which is not the most convenient connector when used in a tight space.
There is so much wonder in the universe; why should you want to imagine that there is more?

paulb
Posts: 811
Joined: Mon Jan 20, 2014 9:02 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by paulb » Wed Mar 29, 2017 2:24 pm

Sorry to divert this thread slightly...
lazarusr wrote:
1024MAK wrote:If the specific DAC chip is hard to get, are there any suitable alternatives?
As you can imagine, I have done quite a bit of research into this. The YM3812 (the main synthesiser) and the YM3014B (the DAC) were very much designed and manufactured as a pair. I have never seen any design using the YM3812 using any other DAC. Equally, I have never seen the YM3014B used for anything other than to decode the output of the YM3812. Subsequent upgrades to the main chip required a different DAC (again, bespoke designed by Yamaha).
I've been looking at the YM2612, which seems to not need the accompanying DAC, although I haven't looked particularly deeply into the matter. But what I was meaning to ask about was the supplier situation and whether you found a decent supplier or not. I've seen one rather prominent Google advertiser mentioned in positive and negative ways in various places, and they appear on eBay and therefore may have been one of your Chinese vendors, but I haven't seen an obviously reliable "normal" Web vendor with any of these kinds of parts. (Unicorn Electronics has the SN76489 and the General Instruments parts.)
lazarusr wrote: In any event, I think patience is currently required. I am sure I will get these chips at a sensible price and without having to find and desolder other boards.
It would be interesting to know if you did find a sensible supplier. Apologies if you didn't and the whole thing was just a hassle!

User avatar
JudgeBeeb
Posts: 808
Joined: Thu Sep 10, 2015 8:56 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by JudgeBeeb » Wed Mar 29, 2017 2:32 pm

The suplier was

Gloria Chan
Bizon Industry Co., Limited
#27C, Block C, Huaqiang Garden, Fuhong Rd.,
Futian Dist., Shenzhen, China
Skype: bizon_ic
infobizon@yahoo.com

I don't know anything about her, but she seems pretty reliable and quick. She takes PayPal - so you have some protection too. I don't think she is really interested in orders for less than 10pcs.
There is so much wonder in the universe; why should you want to imagine that there is more?

Paul
Posts: 114
Joined: Fri Nov 15, 2013 10:39 am
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by Paul » Sun Mar 24, 2019 8:01 pm

Ha.

Sorry to pull up an old thread. But - you know those fun projects you get and plan to spend a spare moment doing? Well, a few years later I managed to finally assemble my BeebOPL music synthesizer.

Very nicely documented and a very well laid out kit. I almost faltered by reaching for my lead-free solder, but luckily read the manual first (an unusual for me). To finish off the weekend, after finding a floppy cable without the twist (I'll make a proper one, but I don't have that specific size of connector!), and a 5v psu. I enjoyed playing music to my son who ran round the living room dancing to the 80s style synth music. Far more fun sounding than the modern PC synths we've been playing with.

Next thing to try is looking through all my Maplins goodies and seeing if I salvaged a box of the right size... And finding some more tracks to convert and seeing if I can work out the code in the juke box....

Anyway - a really nice bit of work there! Well done!

Paul.

User avatar
tricky
Posts: 3585
Joined: Tue Jun 21, 2011 8:25 am
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by tricky » Mon Mar 25, 2019 7:49 am

I confess mine is still unopened and so is one of my matchbox copros! They just keep getting more projects dumped on top of the stack!

User avatar
JudgeBeeb
Posts: 808
Joined: Thu Sep 10, 2015 8:56 pm
Contact:

Re: BeebOPL: an FM Synthesiser for the BBC Micro

Post by JudgeBeeb » Fri Apr 12, 2019 5:45 pm

I confess that I have been fairly busy of late trying to keep on top of my two jobs and haven't had much time to work on any Beeb projects. I have, however, spent some time trying to master micro-soldering. The result, I now have BeebOPL nano working (including two QFN packages) with, of course, the obligatory bodge wires.

IMG_0303.jpg
There is so much wonder in the universe; why should you want to imagine that there is more?

Post Reply